Electrochemical reactor

An electrochemical reactor arranged in an exhaust passage of an internal combustion engine, wherein

• the electrochemical reactor comprises a honeycomb member at which a plurality of cells are formed, the honeycomb member comprising an upstream side partial honeycomb member and a downstream side partial honeycomb member arranged at a downstream side from the upstream side partial honeycomb member in the direction of exhaust flow;
• the upstream side partial honeycomb member comprises a plurality of first cells and a plurality of second cells arranged so as to at least partially adjoin the first cells through partition wall base members including an ion conductive solid electrolyte, a cathode layer being provided on the surface of the partition wall base members defining the first cells and an anode layer being provided on the surface of the partition wall base member defining the second cells;
• the downstream side partial honeycomb member comprises a plurality of third cells and a plurality of fourth cells arranged so as to at least partially adjoin the third cells through partition wall base members including an ion conductive solid electrolyte, an anode layer being provided on the surface of the partition wall base members defining the third cells and a cathode layer being provided on the surface of the partition wall base members defining the fourth cells;
• and
• the electrochemical reactor is configured so that all of the exhaust gas flowing through the first cells flows into the third cells and all of the exhaust gas flowing through the second cells flows into the fourth cells.